Retain references to surfaces from both active AND pending CompositorFrames

cc/surfaces/surface_dependency_tracker.cc

Index: cc/surfaces/surface_dependency_tracker.cc
diff --git a/cc/surfaces/surface_dependency_tracker.cc b/cc/surfaces/surface_dependency_tracker.cc
index 934586bbb53757c654ba28c6d660b1359ff06ced..df201520f458dd5f6cac01f82445d1eec440b407 100644
--- a/cc/surfaces/surface_dependency_tracker.cc
+++ b/cc/surfaces/surface_dependency_tracker.cc
@@ -26,6 +26,9 @@ SurfaceDependencyTracker::SurfaceDependencyTracker(
 SurfaceDependencyTracker::~SurfaceDependencyTracker() {
   surface_manager_->RemoveObserver(this);
   begin_frame_source_->RemoveObserver(this);
+  for (Surface* pending_surface : pending_surfaces_)
+    pending_surface->RemoveObserver(this);
+  pending_surfaces_.clear();
 }
 
 void SurfaceDependencyTracker::RequestSurfaceResolution(Surface* surface) {